1. Field of the Invention
The present invention relates to a semiconductor device and a method for driving the semiconductor device. Specifically, the present invention relates to an image sensor provided with a photosensor in each of a plurality of pixels, and a method for driving the image sensor. The present invention further relates to an electronic device including the image sensor.
Note that a semiconductor device refers to a semiconductor element itself or a device including a semiconductor element. As an example of such a semiconductor element, for example, a thin film transistor can be given. Therefore, the semiconductor device includes a liquid crystal display device, a memory device, and the like.
A photosensor refers to one element provided in a pixel, and an image sensor refers to a device including a plurality of pixels each provided with a photosensor.
2. Description of the Related Art
Image sensors are widely used these days. Image sensors are required to have high resolution, and with an increase in the resolution of image sensors, data processing speed also continues to increase.
In addition, image sensors are required to have a wider dynamic range. One of proposed methods for widening the dynamic range of an image sensor is to provide a difference arithmetic circuit in each pixel (e.g., Patent Document 1).